The development of amphetamine-ion-selective microelectrodes using electrochemical polymerization and microfabrication technologies is reported in this study. The microelectrodes include polypyrrole films electrochemically polymerized and doped with cosane anion ([3,3-Co(1,2-C2B9H11)(2)](-)) as the internal solid contact layer between the polymeric sensitive membrane and platinum working microelectrode. Several poly(vinyl chloride)-type membranes with different compositions of plasticizers/ionophore were drop casted on the conducting polymer layer, polypyrrole[3,3-Co(1,2-C2B9H11)(2)]. Potentiometric measurements were performed to calibrate the response of the developed chemical sensors. The sensor was highly sensitive to amphetamine using a membrane composition of 26wt% poly (vinyl chloride), 63wt% di-butyl phthalate, 6wt% sodium tetraphenylborate, and 5wt% dibenzo-18-crown 6-ether. A high and linear response was demonstrated within the concentration range from 10(-5) to 10(-3)M with a slope of 53mV/decade and a limit of detection of 4x10(-5)M. A Reilley diagram shows that the sensor signal is stable for a working pH between 1.50 and 8.50. The chemical sensor was highly selective to amphetamine when compared to other interfering ions and compounds including K+, Na+, NH4+, D,L-phenylalanine, caffeine, (+/-)-epinephrine bitartrate salt, and N-formylamphetamine using the fixed interference method with coefficients of selectivity (Log K-IJ(Pot)) from -1.40 to -1.15.